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Jacob and Monod proposed the lac operon of E. coli. The lac operon contains a promoter, an operator, and three structural genes called z, y, and a, coding for the enzyme, β galactosidase, permease and transacetylase respectively. The lac regulator gene, designated as i gene, codes for repressor. In the absence of the inducer, the repressor binds to the lac operator, preventing RNA polymerase from binding to the promoter and thus transcribing the structural genes.

1. True
2. False
3. Partially true
4. None of these

Correct answer: True

Solution

The lac operon of E. coli was indeed proposed by Jacob and Monod, and it consists of a promoter, an operator, and three structural genes that code for the enzymes β-galactosidase, permease, and transacetylase. The lac regulator gene, designated as the i gene, codes for the repressor protein.

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